1. Field of the Invention
The present invention relates to an apparatus for supporting a winding on a stator, in particular on a generator stator in a power station.
2. Brief Description of the Related Art
Normally, a stator, in particular a generator stator in a power station, has a core as well as a winding which has two or more winding bars. The ends of these winding bars are passed out of the core at at least one axial end face of the core of the stator, and are thus bent around and connected to one another such that they form an end winding on the end face of the core, which widens in the form of a funnel or in the form of a cone as the distance from the core increases. For operation of the stator, this end winding must be supported in the axial direction of the stator, that is to say axially, with tensile stress being applied to the core. Furthermore, the end winding must be loaded radially from the outside to the inside by means of prestressing. This stressing or support of the end winding is necessary in order to make it possible to absorb the electrodynamic forces which occur during operation. In some cases, the desired bracing of the winding and of the end winding is applied even during the manufacture of the stator. However, seating processes and the like may occur during operation of the stator which may have a disadvantageous effect on the stress acting on the winding and on the end winding.
U.S. Pat. No. 5,798,595 discloses a supporting apparatus in which the end winding is braced and is radially supported with the aid of supporting rings. The supporting rings in this case extend in the circumferential direction and surround the outer face of the end winding. The end winding is in this case supported on the outside of these supporting rings at right angles to its envelope surface. These supporting rings allow a predetermined prestress to be applied to the end winding during the manufacture of the stator winding. However, this stress may decrease as a result of seating processes. In the case of the known supporting apparatus, the winding supports each have an associated damping device which operates with compression springs that are arranged between the respective winding support and the supporting rings. This results in a sprung bearing for the supporting rings on the winding supports. At the same time, the compression springs can produce axial bracing for the winding. However, the compression springs cannot provide additional radial bracing, or bracing at right angles to the envelope surface, of the end winding, since the supporting rings absorb the spring forces in this direction.
U.S. Pat. No. 4,488,079 discloses a further supporting apparatus for an end winding, in which the end winding is stiffened with the aid of bracing plates, which are arranged radially on the outside of the end winding. The winding supports are then supported radially and at right angles to the envelope surface on the bracing plates of the end winding.